Anyone trying to read the tea leaves from today's supreme court oral argument on the Prop 8 case ought to act with caution. Last term's blockbuster surprise in the case upholding Obamacare is only the most recent evidence of how easy it is for even seasoned observers of the court to misread the significance of the justices' questions for the ultimate decision. This is the first sense in which caution is key, but let me suggest different ways that caution might also be seen as the theme of the day.

There was a palpable sense of caution about whether the court should even reach a decision on the merits of the case. The all star legal team of Ted Olson and David Boies, representing those challenging Prop 8, swung for the fences, as it were, and asked the court to find a fundamental right to same-sex marriage that would apply to every state in the country. To the extent the justices' questions signal anything of substance, they suggest very little interest in going remotely that far. Indeed, my strongest impression from the arguments is there is a significant chance that the court may well not reach the constitutional question in the case.

The court could pursue two routes in avoiding the merits: One was extensively briefed and discussed before today's argument, the other is far more hazy and was not anticipated by many observers at all. The so-called "standing" issue was the one that the court asked the advocates to brief and argue. This question asks whether those who sponsored Prop 8 when it was before the voters have the legal right to pursue an appeal defending it when the state officials who normally do that, the governor and the state attorney general, declined to do so. This issue boils down to the question whether the ballot sponsors are more like citizens with strong policy views about a law (who normally cannot defend a law in federal court) or, instead, surrogate public officials who can act as the state for purposes of this lawsuit when the state itself refuses to do so (who would be permitted to defend the law).

Both positions raise problems in ways vigorously pressed by the justices. How can citizens act as public officials when they have no duty or accountability to voters and were never appointed to act as the state? On the other hand, how can public officials be permitted to nullify ballot initiatives by choosing not to defend them when the whole purpose of the initiative process is to let voters, not elected officials, decide the issue? This last point seemed to draw some sympathy from Justice Anthony Kennedy, who hails from California and is well versed in the central role of the initiative process in the state's political culture.

The considerable attention paid to standing was not a surprise. What was a surprise was that Justice Kennedy – typically the swing voter on the court – twice raised the possibility that the court should never have granted review in the case at all. At one point, Justice Sonia Sotomayor chimed in with sympathy for this position. The question this raised for aficionados of supreme court procedure is whether the court might use a device called "dismissing a case as improvidently granted". It took only four justices to grant review in the first place – presumably the more conservative four in this case. Would five justices "DIG" the case now if the four who voted for review still want to decide it? Once again, caution is the word of the day, and it may turn out that Kennedy lacks real interest in – or simply cannot corral the votes for – a dismissal option.

If either the ballot sponsors are found to lack standing or the case is somehow otherwise dismissed, it would reflect a deeply cautious approach because it would keep the high court from deciding for now what states must do about same-sex marriage. It would, though, leave intact a lower court ruling striking down Prop 8, and would mean that marriages would resume in California, with future litigation in the state a real possibility.

What did we learn about the justices' views on the merits of the constitutional question? As was predictable, there is plenty of disagreement on the court. Swing Justice Kennedy did express real concern for the welfare of children raised by same-sex couples, given that California policy seem to tell them that their families did not deserve equal recognition. But here is what struck me: there was very little evidence that any justice, including Justice Kennedy and including the more progressive ones, was interested in a ruling that would impose marriage equality nationally.

I doubted before the argument that the court would move in that dramatic direction (notwithstanding the invitation to do so extended by Olson and Boies) and nothing today changed that. Among the more conservative justices, there was a plea for caution in having more time to see the "results" of same-sex marriage before condemning a ban on it as unconstitutional. Justice Samuel Alito, for example, noted that same sex marriage was newer than cellphones or the internet.

Among the more progressive justices, there was a different kind of plea for caution. They suggested caution about signaling states that they should not pursue civil union-type measures, as California had done. Several justices expressed great skepticism about the idea that they could plausibly strike down Prop 8 with an opinion limited to California or to the 9 states that allow comprehensive marriage-like rights to same-sex couples, but do not permit access to marriage per se. This is the path argued for by the Obama Administration, and was the basic theory of the Ninth Circuit's decision striking down Prop 8. The key idea for those advancing this argument is that once a state grants same-sex couples all the rights of marriage – most especially parental rights and the right to adopt children – it can no longer defend a ban on same-sex marriage based on ideas about children. It has surrendered those arguments. But various justices quickly saw the irony here: can it be, they asked, that the states that grant the greatest rights to same-sex couples are really the most constitutionally vulnerable? In other words, is it conceivable that California runs afoul of the Constitution, but a state like Mississippi, which offers same-sex couples no real rights, does not?

Here is where caution came back in. Several justices suggested that the court ought to be wary about telling states that if they grant more rights to same-sex couples through civil unions or domestic partnerships, they will be "penalized," in Justice Kennedy's words, by being forced to offer marriage. Creating that kind of negative incentive, Justice Stephen Breyer said, is a "real world effect" the court should carefully consider.

What does all this mean? If the four more progressive justices plus Kennedy have little appetite for a 50 state, a nine state or a one state decision on the merits, then dismissing the case for lack of standing or on some other basis seems most likely. Given that Kennedy also expressed concern with leaving ballot initiatives defenseless when elected officials decline to defend them, that might well put us in the mystery category of how else this case might be dismissed. Or, there may be a different five – perhaps with the Chief Justice along – to dismiss based on lack of standing. We will learn more as soon as tomorrow, as the court turns to the federal Defense of Marriage Act. The issues are different there, and it strikes me as far more likely that the court will decide on the merits whether this federal statute can stand. But there are also procedural escape routes in that case. If five members of the court are feeling as cautious tomorrow as they seemed today, it may be time for Americans to take a lesson in the arcana of supreme court jurisdiction.